Arthur Sinodinos has enjoyed a reputation as a whip-smart details politician, which is why his appointment as Assistant Treasurer made sense.
In the crucial role he could be counted upon, with the Treasurer, to stay across every aspect of the national accounts.
This carefully earned reputation was all but exploded during five hours in the witness box at the Independent Commission Against Corruption on Thursday.
Grilled by counsel assisting, Geoffrey Watson, about what he knew of the profligate spending of infrastructure company Australian Water Holdings, Sinodinos claimed almost total ignorance.
There was the $164,275 spent on a corporate box at Stadium Australia; $28,738 on limousine hire; the $159,500 in retainer payments to Solutions R Us, a lobbying company owned by Liberal fundraiser Paul Nicolaou.
On top of all that there was more than $70,000 in political donations to the NSW Liberal Party, but Sinodinos - party treasurer and AWH director at the time - insists he was unaware of the lot.
Worse, he agreed some of this occurred during periods when AWH was experiencing cash-flow problems so serious it struggled to pay its tax and even employee superannuation.
But perhaps most damning of all was the admission he did not look closely at the AWH accounts before joining the board.
Why not? ''Because I was joining the board and I was going to learn about the company while I was on the board,'' he explained.
The ICAC has heard that most if not all of these expenses were being cynically charged back to state-government owned Sydney Water via a loophole in a contract AWH had to provide infrastructure in Sydney's north-west.
So in one sense the lack of knowledge shields Sinodinos from the charge he willingly engaged in ripping off the NSW taxpayer.
But the other consequence of this admission is the shredding of his reputation as a financial manager.
When Sinodinos stepped aside as assistant Treasurer, Prime Minister Tony Abbott said he looked forward to his ''restoration to the ministry'' once cleared by the ICAC.
It is unlikely voters will agree.